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a(n) = [[(k^2)*n]-(k*[k*n])], where k = cube root of 2 and [] is the floor function.
2

%I #2 May 01 2014 02:46:11

%S 0,-1,0,0,-1,-1,0,0,-1,0,-1,0,0,-1,0,0,-1,-1,0,1,-1,0,-1,0,0,-1,0,-1,

%T -1,0,0,-1,-1,0,0,-1,0,0,0,-1,0,0,0,-1,-1,0,1,-1,0,0,0,-1,0,0,-1,0,-1,

%U 0,0,-1,0,0,-1,0,0,0,-1,0,-1,0,0,-1,0,0,-1,0,0,-1,-1,0,0,-1,0,-1,0,-1,-1,0,0,-1,-1,0,1,-1,0,0,0,-1,0,0,0,-1,-1,0,-1,-1,0,0,-1,0,0,0,-1,0,-1,0,0,-1,0,0

%N a(n) = [[(k^2)*n]-(k*[k*n])], where k = cube root of 2 and [] is the floor function.

%C The values of (floor((k^2)*j)-(k*(floor(k*j)))) for j=0..50, where k=2^(1/3), are 0, -0.259921, 0.480158, 0.220237, -0.299605, -0.559526, 0.180553, 0.92063, -0.59921, ...

%p Digits := 89; floor_diffs_floored(evalf(2^(1/3)),120);

%Y A059648 gives similar sequence for k=sqrt(2). Positions of +1's: A059657, positions of -1's A059659.

%K sign

%O 0,1

%A _Antti Karttunen_, Feb 03 2001